Precision initiation coupler

ABSTRACT

A device for funneling a detonation wave from a detonator to a main explosive charge to substantially eliminate the detrimental effects of axial misalignment of the detonator and main explosive charge, comprising a detonation-confining body carrying therein a generally I-shaped explosive extending axially through it. The device is placed between a detonator and main charge and in axial alignment with the latter. A detonation wave from the detonator may be eccentrically received by one end of the I-shaped explosive, but it is funnelled down the column of the I, which is in axial alignment with the main charge, so that the latter &#39;&#39;&#39;&#39;sees&#39;&#39;&#39;&#39; an axially-aligned detonation wave emanating from the other end of the I. The explosive, the material forming the detonation-confining body and the dimensions of the I-shaped charge are selected to insure that there is substantially no interference with the detonation of the I-shaped explosive, to preferably maximize the detonation velocity through the explosive, and to ensure that detonation of the main explosive is initiated from the I-shaped explosive and not from the confining body.

States Zernow et al.

atent 91 [54] PRECISION INITIATION COUPLER [75] Inventors: Louis Zernow,Glendora, Arthur Louis Mottet, Pacific Palisades, both of Calif.

[73] Assignee: Whittaker Corporation [22] Filed: Dec. 23, 1970 [21]Appl. No.: 91,664

Primary Examiner -verlin R. Pendegrass Att0rney-D0nald E. Nist and Jayl-l. Quartz [57] ABSTRACT A device for funneling a detonation wave froma detonator to a main explosive charge to substantially eliminate thedetrimental effects of axial misalignment of the detonator and mainexplosive charge, comprising a detonation-confining body carryingtherein a generally l-shaped explosive extending axially through it. Thedevice is placed between a detonator and main charge and in axialalignment with the latter. A detonation wave from the detonator may beeccentrically received by one end of the I-shaped explosive, but it isfunnelled down the column of the l, which is in axial alignment with themain charge, so that the latter sees" an axially-aligned detonation waveemanating from the other end of the l. The explosive, the materialforming the detonation-confining body and the dimensions of the I-shapedcharge are selected to insure that there is substantially nointerference with the detonation of the l-shaped explosive, topreferably maximize the detonation velocity through the explosive, andto ensure that detonation of the main explosive is initiated from theI-shaped explosive and not from the confining body.

10 Claims, 3 Drawing Figures PATENIEDJM 2 I975 6 my M mo J M Z0 L 9PRECISION INITIATION COUPLER BACKGROUND OF THE INVENTION This inventionrelates to explosive charges and, more particularly, to explosivedevices in which a detonator is used to initiate detonation of a maincharge.

Manufacturing tolerances in the metal parts of fuzing systems used inshaped charge ammunition, as well as the variations in the symmetry ofthe output of fuze detonators, often results in a net eccentricity ofthe point of initiation of the shaped charge relative to its axis. Forprecision shaped charge assemblies, this eccentricity of the initiationcan result in significant degradation of the shaped charge performance.For example, losses up to 25. perce ntand more may result from aneccentricity of initiation on the order of 0.150 inches.

SUMMARY OF THE INVENTION This invention is embodied in a precisioninitiation coupler which is designed to be placed between a detonatorand a main charge to correct any misalignment of the axes of thedetonator and main charge which could reduce the effectiveness of theoutput of the main charge. This invention can be employed with anycombination of explosive charges where the effectiveness of thecombination of charges is dependent on alignment of the axes of thecharges making up the combination. However, this invention, at present,has particular utility when employed with shaped charge ammunition.

In brief, the invention comprises a detonation-confining body having anI-shaped cavity formed therein and extending through the confining body.The cavity is axially aligned with the axis of the confining body and isfilled with an explosive to provide an explosive charge with an I-shapedconfiguration. The precision initiation coupler is axially aligned withthe main charge and, when in this position, is not axially aligned witha misaligned detonator. However, the particular 1- configuration of theexplosive in the coupler is such that the eccentric detonation wave fromthe detonator is received and transmitted by one end of the I-shapedcharge through the web or column section of the I which is axiallyaligned with the main charge. The detonation wave is thus axiallytransmitted through the other end of the I-shaped charge and this, inturn, produces axially aligned detonation of the main charge.

The advantage of employing the precision initiation coupler of thisinvention is that it can substantially eliminate the effect ofmisalignments between detonators and main charges which the former areemployed to detonate. For example, it can reduce detonator inputeccentricities to the coupler as large as 0.150 inches to coupleroutputs having a residual eccentricity of 0.01 inches and less. Thisalignment correction is accompanied by a substantial increase in maincharge effectiveness and this increase in effectiveness may be as muchas 30 percent or more depending upon the particular application. Use ofthe herein-described coupler also eliminates the necessity of employingclose tolerances in fuzing systems thereby reducing the cost of suchsystems normally associated with the maintenance of close tolerances.These advantages are obtained with a coupler which is of simple designand which can be readily and inexpensively assembled.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theprecision initiation coupler of this invention.

FIG. 2 is an elevational sectional view of the coupler of FIG. 1 takenalong the line 2-2 of FIG. 1.

FIG. 3 is an elevational sectional view of a simplified shaped chargesystem illustrating the use of the hereindescribed coupler incombination with a fuze body and a shaped charge.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2,the numeral 10 designates a precision initiation coupler of thisinvention. The coupler 10 comprises a normally cylindrical body 12 whichis provided with an axially aligned cavity 14. The cavity 14 has agenerally I-shaped configuration. As shown in FIGS. 1 and 2, the cavity14 is symmetrical about its transverse axis. However, it need not be aswill be further described hereafter.

The terms upper and lower are used herein for simplicity of descriptionand otherwise have no significance since the coupler 10 does not have tobe used in an axially vertical position.

The cavity 14 comprises a pair of expanded-diameter, normally-circular,end sections 16,18 which open through upper and lower faces 20,22,respectively in the coupler body 12 and which are in communication witheach other through a channel 24 of circular crosssection andsubstantially smaller diameter. The walls of the channel 24 at theirjuncture with the walls of the cavity end sections 16,18 are preferablytapered to facilitate filling of the cavity 14 and to continuedetonation upon emergence. Detonation may become extinguished if gradualemergence provided. In FIGS. 1 and 2, the cavity 14 is shown assymmetrical about its transverse axis. This is preferred because thecoupler 10 can be oriented to make either end the input end. However, itis not essential as will be further described hereafter.

The cavity 14 is filled with an explosive, such as RDX (cyclonite), PETN(pentaerythritol tetranitrate) and tetryl, so that a generally I-shapedexplosive charge 26 conforming to the configuration of the cavity 14 isformed within, and coaxial with, the coupler body 12. The explosivecharge 26 comprises upper and lower, disc-shaped flange sections 28,30,respectively, which are interconnected by a column 32. The upper flange28 has an exposed face 34 which receives detonation waves from adetonator which causes initiation of the explosive in the upper flangesection 28. The detonation front from the latter is transmitted throughthe column 32 to the lower flange section 30, which, in turn, serves todetonate any explosive adjacent to its exposed face 38. Although thepoint of initiation at the face 34 of the upper flange section 28 may beeccentric with respect to the longitudinal or detonation axis of thel-shaped charge 26, it is funnelled through the axially-aligned column32 to emerge at the face 38 of the lower flange section 30 withsubstantially no eccentrici- The dimensions of the I-shaped explosivecharge 26, and thus of the cavity 14, are determined by a number ofvariables which, to some extent, are unique to each application. TheI-shaped charge 26 is, therefore, essentially tailored to meet therequirements of each application. If the upper flange section 28 of theI-shaped charge 26 is the input end, its diameter must be sufficient toprovide an area of the exposed face 34 so that the latter can acceptinputs from a wide range of possible displacements of a point ofinitiation on its surface from the longitudinal axis of the l-shapedcharge. On

the other hand, the size of the lower flange section 30 is determined byits ability to provide an adequate input to the explosive charge, e.g.,a booster charge, adjacent to it. That is, it must be sufficiently largeto ensure good initiation of the booster or main charge where thisdevice may be employed as the booster. its size will thus depend uponthe type of explosive employed in the I-shaped charge 26, the explosivewhich is to be detonated, and the efficiency with which it, itself, isdetonated. It will be understood that since different parameters governthe sizes of the upper and lower flange sections 28,30, they may be ofdifferent size and the l-shaped charge 26 need not be symmetrical aboutits transverse axis.

The diameter of the column 32 of the l-shaped charge 26 should be largeenough to propogate the detonation wave from the upper flange section 28to thereby cause initiation of the lower flange section 30. This will bea function of the type of explosive employed in the l-shaped charge 26and the confinement provided by the material forming the coupler body12. In general, the greater the degree of confinement, the smaller thediameter of the column 32 that can be used. The length of the column 32is preferably as long as possible for a given length of I-shaped charge26 to reduce the total amount of explosive in the precision initiationcoupler in order to reduce shock transfer through the coupler body 12which can have deleterious effects as described hereafter.

A high detonation velocity through the explosive in the l-shaped charge26 is preferred to ensure that detonation of the explosive next to bedetonated, e.g., a booster, results only from detonation of the l-shapedcharge 26 and to ensure that the output of the l-shaped charge ismaximized. In addition to selecting an explosive for the I-shaped charge26 which exhibits a high detonation velocity, the material forming thecoupler body 12 is preferably selected so that the detonation front issubstantially confined to the explosive in the lshaped charge, that is,so that shock waves, from the explosive detonation, through the couplerbody material are minimized. In this way, there is less chance that ashock traveling through the coupler body material will interfere withthe detonation front propogated through the explosive and thus weaken orcause the latter to become eccentric. Additionally, by reducing shockspassing through the coupler body 12, there is less chance that, forexample, an adjacent booster, will be detonated by such shocks ratherthan by detonation of the I-shaped charge 26, thereby ensuringcorrection of asymmetrical alignment by the herein-described coupler.

The material forming the coupler body 12 may be a metal such as steel oraluminum, or a plastic such as a microballoon filled phenolic. Atpresent, it is preferable to employ steel as the coupler body materialsince this provides excellent detonation confinement.

In general, the precision initiation coupler 10 is placed between adetonator and a main charge. However, in practice, the coupler 10 isnormally placed between a detonator and a booster which, in turn, servesto detonate a main charge. Such an arrangement is shown in thesimplified warhead assembly of FIG. 3. As shown therein, a fuze body 40is placed adjacent a booster cup 42 which, in turn, is placed against amain explosive charge 44, such as a shaped charge. These components arelocated within a warhead body (not shown). The fuze body 40 contains, insimplified form, a firing pin 46 and, a detonator charge 48 (which mayconsist of a plurality of charges).

The precision initiation coupler 10 may be positioned within the fuzebody 40 or it may be positioned within the booster cup 42 as shown inFIG. 3. The booster cup 42 is divided into two sections with the coupler10 in one section and a booster pellet 50 in the other section. The sidewalls of the booster cup 42 automatically align the detonation axis 52of the coupler 10 with the detonation axis 54 of the booster pellet 50which, in turn, is axially aligned with the main charge 44, whereas, thecoupler 10 is usually not in alignment with the detonation axis 56 ofthe detonator 48 in the fuze body 40 due to machining limitations andtolerances. However, the axis of the detonator 48 terminates within thearea of the exposed face 34 of the lshaped charge 26 so that thedetonation wave from the detonator first impinges on the coupler 10within that area.

In operation, a force impacts the front end of the warhead causing thefiring pin 46 to strike the detonator 48 to cause initiation of thelatter. The resulting detonation wave eccentrically initiates detonationof the explosive in the l-shaped charge 26 due to the fuze body-boostercup misalignment. However, because of the particular configuration ofthe I-shaped charge 26, the explosive detonation wave is forced totravel down the axially-aligned column 32 so that the lower flangesection 30 of the l-shaped charge sees only a substantiallyaxially-aligned output from the l-shaped charge 26 to the booster pellet50.

EXAMPLE A precision initiation coupler was made up as shown in FIGS. 1and 2. The coupler body was formed from steel and was provided with athickness of 0.290 in. and a diameter of 0.750 inches. The cavity and,thus, the I- shaped charge, had the following dimensions: diameter ofupper and lower end sections 0.4 in.; diameter of channel at itsthinnest section 0.050 inches; and depth of upper and lower end sections(flange thickness) 0.075 inches. The l-shaped charge was formed frompressed RDX.

The coupler was placed in an assembly as shown in FIG. 3 except that nomain charge was present. The misalignment of the detonator input to thecoupler with respect to the longitudinal axis of the latter was 0.100inches. The assembly was fired and photographs showed that misalignmentof the output from the coupler was less than 0.010 inches. Comparisonstudies of this arrangement with and without the coupler that outputscould be increased as much as 35 percent with the coupler.

We claim:

1. A precision initiation coupler, comprising:

a detonation-confining body having an l-shaped cavity formed therein andextending axially through said body; and

a detonating explosive substantially filling said shaped cavity.

2. The coupler of claim 1 wherein said detonating explosive is selectedfrom the group consisting of RDX, tetryl and PETN.

3. The coupler of claim 2 wherein said material forming said confiningbody is a metal.

4. The coupler of claim 2 wherein the material forming said confiningbody is a plastic.

5. The coupler of claim 3 wherein said metal is one of the groupconsisting of steel and aluminum.

6. The coupler of claim 1 wherein said I-shaped cavity is symmetricalabout its transverse axis.

7. An explosive device, comprising:

a first explosive charge;

a second explosive charge for detonating said first explosive charge,each said explosive charge having an axis ideally centering a detonationwave passing through each said explosive charge when detonated;

a precision initiation coupler comprising a detonation confining bodyhaving an l-shaped cavity axially-formed therein and extending throughsaid body to open through opposing ends of said body, said cavity beingsubstantially filled with a detonating explosive to provide saiddetonating explosive with an I-shape having a pair of exposed end faces,said precision initiation coupler positioned in axial alignment withsaid first explosive charge and adjacent said first and said secondexplosive charges so that detonation of said second explosive charge istransmitted through said precision initiation coupler to detonate saidfirst explosive charge, said axis of said second explosive chargeterminating within the area of said one exposed end face of saidl-shaped detonating explosive which is adjacent said second explosivecharge, whereby detonation of said second explosive charge received bysaid one exposed end face is funnelled through said l-shaped detonatingexplosive to exit at said other exposed end face in substantial axialalignment with said first explosive charge.

8. The explosive device of claim 7 wherein said first explosive chargeis a booster and wherein said second explosive charge is a detonator.

9. The explosive device of claim 7 wherein said detonation-confiningbody is formed from a metal selected from the group consisting of steeland aluminum.

10. The explosive device of claim 7 wherein said cavity is symmetricalabout its transverse axis.

1. A precision initiation coupler, comprising: a detonation-confiningbody having an I-shaped cavity formed therein and extending axiallythrough said body; and a detonating explosive substantially filling saidI-shaped cavity.
 2. The coupler of claim 1 wherein said detonatingexplosive is selected from the group consisting of RDX, tetryl and PETN.3. The coupler of claim 2 wherein said material forming said confiningbody is a metal.
 4. The coupler of claim 2 wherein the material formingsaid confining body is a plastic.
 5. The coupler of claim 3 wherein saidmetal is one of the group consisting of steel and aluminum.
 6. Thecoupler of claim 1 wherein said I-shaped cavity is symmetrical about itstransverse axis.
 7. An explosive device, comprising: a first explosivecharge; a second explosive charge for detonating said first explosivecharge, each said explosive charge having an axis ideally centering adetonation wave passing through each said explosive charge whendetonated; a precision initiation coupler comprising a detonationconfining body having an I-shaped cavity axially-formed thErein andextending through said body to open through opposing ends of said body,said cavity being substantially filled with a detonating explosive toprovide said detonating explosive with an I-shape having a pair ofexposed end faces, said precision initiation coupler positioned in axialalignment with said first explosive charge and adjacent said first andsaid second explosive charges so that detonation of said secondexplosive charge is transmitted through said precision initiationcoupler to detonate said first explosive charge, said axis of saidsecond explosive charge terminating within the area of said one exposedend face of said I-shaped detonating explosive which is adjacent saidsecond explosive charge, whereby detonation of said second explosivecharge received by said one exposed end face is funnelled through saidI-shaped detonating explosive to exit at said other exposed end face insubstantial axial alignment with said first explosive charge.
 8. Theexplosive device of claim 7 wherein said first explosive charge is abooster and wherein said second explosive charge is a detonator.
 9. Theexplosive device of claim 7 wherein said detonation-confining body isformed from a metal selected from the group consisting of steel andaluminum.
 10. The explosive device of claim 7 wherein said cavity issymmetrical about its transverse axis.